Saturday, 10 June 2017

Successful Tests for Diesel - Liquid Nitrogen Hybrid

A revolutionary hybrid bus that runs on both diesel and liquid
nitrogen has completed a rigorous series of trialsat MIRA to bring it one step
closer to the road.

The hybrid bus – CE Power – is the world’s first to be powered by
liquid nitrogen and has been built by engineers at HORIBA MIRA as part
of an Innovate UK consortium. The bus utilises alternative propulsion to
address urban air pollution challenges and features a high-efficiency,
zero emission Dearman Engine, powered by liquid nitrogen, alongside a
conventional diesel engine. The hybrid system enables the bus to reduce
noxious tail-pipe emissions, improving local air quality.
The Innovate UK consortium was comprised of leading industry,
academic and local and national governmental organisations. It was led
by Dearman and included Air Products, Cenex, Coventry University,
Dearman, HORIBA MIRA, Manufacturing Technology Centre, Productiv Ltd,
and TRL (the Transport Research Laboratory).
The bus uses a hybrid propulsion system to reduce emissions during
acceleration after stopping. This portion of the bus’s drive cycle
traditionally has a heavy impact on the diesel engine and can produce
vast amounts of nitrogen oxide and carbon dioxide emissions. As the
Dearman Engine produces none of these harmful emissions, it will enable
the bus to continue to frequently stop to unload and pull away from a
bus stop without expelling the same level of damaging pollutants.
Whilst driving at 20 mph or below, the liquid nitrogen – stored in a
low pressure insulated cylinder – is warmed up to the point of boiling,
at which time it creates enough pressure to drive the multi-cylinder
Dearman engine. Once the bus reaches 20 mph, the diesel engine will kick
in as at this speed the bus requires less effort from the engine to
operate.
The bus trials were completed at HORIBA MIRA’s engineering facilities
and Proving Ground in Nuneaton and included components and full system
testing along with an engineered drive cycle to simulate a standard bus
route with a variety of stops.

Martin Watkinson, Technical Lead on the project at HORIBA MIRA, said:
“The hybrid nature of CE Power demanded a sleek systems integration
process. Our engineers worked to ensure the liquid nitrogen system
operates seamlessly and safely with the diesel engine, in addition to
carrying out the whole vehicle thermodynamics modelling and the overall
vehicle control and testing.
“The completion of these trials paves the way for the use of liquid
nitrogen more widely in the automotive sector, and takes the UK one step
closer to stamping out harmful emissions for good.”

David Sanders, Commercial Director at Dearman commented:
“As the UK wrestles with dangerous levels of urban air pollution, a
bus that runs on ‘thin air’ represent a significant breakthrough. The
Dearman Engine has the potential to significantly improve the efficiency
of both buses and HGVs, reducing fuel consumption and cutting
pollution. Crucially it can provide a cost effective alternative to
other emerging zero emission technologies, whose environmental
performance if often offset by complexity and cost. This successful
trial could be the first step towards rolling out a British innovation
to the streets of the UK and around the world.”

Jonathan Reid, Technical Lead on the project at the Manufacturing Technology Centre (MTC), said:
“This project has enabled the MTC and the consortium to begin the
journey of advancing the UK cryogenic supply chain from a niche industry
to one capable of mass manufacture. The Dearman Engine will create
high-skilled jobs, growing UK capability in state of the art manufacture
of cryogenic systems.”

Jon Trembley, Head of Cryogenic Technology at Air Products added:
“The developing of an on-vehicle cryogenic system was a notable
achievement to come from the project. The innovative system was
developed by the consortium team to store cryogenic nitrogen liquid at
low pressure, then pressurise and store in high pressure cylinders for
use in the Dearman engine. This stored pressure is then used to provide
the rapid reaction pressure responses required.”

Peter Speers, Principal Technical Specialist at Cenex, commented:
“Cenex was responsible for modelling the operation of the Dearman
hybrid system in the bus, with its predictions tallying with real-world
test results. Cenex also conducted the first Life Cycle and Total Cost
of Ownership analyses of the Dearman system in bus operation. With
diesel-fuelled buses one of the major causes of harmful NOx emissions in
our towns and cities, Cenex was delighted to help trial this innovative
technology because it has the potential to significantly reduce these
emissions.”

The benefits of using liquid nitrogen over an electric hybrid bus
include a much longer life, local production and easy refuelling.
Batteries, which power many of the UK’s electric hybrids, require
changing several times over the course of a bus’s lifetime, whereas the
liquid nitrogen system will last the lifetime of the bus. Liquid
nitrogen can be produced locally without the need for neodymium or
lithium, which are both used by motors and batteries and sourced from
overseas. Furthermore, refuelling liquid nitrogen can take a matter of
minutes, enabling the bus to return to the road in a short timeframe.

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